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BACTERIAL SORPTION OF HEAVY METALS
Citation:
Mullen, M., D. Wolf, F. Ferris, T. Beveridge, C. Flemming, AND G. Bailey. BACTERIAL SORPTION OF HEAVY METALS. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-89/319 (NTIS PB90200692).
Description:
Four bacteria, Bacillus cereus, B. subtilis, Escherichia coli, and Pseudomonas aeruginosa, were examined for the ability to remove Ag+, Cd2+, Cu2+, and La3+ from solution by batch equilibration methods. d and Cu sorption over the concentration range 0.001 to 1 mM was described by Freundlich isotherms. t 2 mM concentrations of both Cd2+ and Cu2+, P. aeruginosa and B. cereus were the most and least efficeint at metal removal, respectively. reundlich K constants indicated that E. coli was most efficient at Cd2+ removal and B. subtilis removed the most Cu2+. emoval of Ag+ from solution by bacteria was very efficient; an average of 89% of the total Ag+ was removed from the 1 mM solution, whereas only 12, 29, and 27% of the total Cd2+, Cu2+, and La3+, respectively, were sorbed from 1 mM solutions. lectron microscopy indicated that La3+ accumulated at the cell surface as needlelike, crystalline precipitates. Silver precipitated as discrete colloidal aggregates at the cellsurface and occasionally in the cytoplasm. either Cd2+ nor Cu2+ provided enough electron scattering to identify the location of sorption. he affinity series for bacterial removal of these metals decreased in the order Ag>La>Cu>Cd. he results indicate that bacterial cells are capable of binding large quantities of different metals. dsorption equations may be useful for describing bacterium-metal interactions with metals such as Cd and Cu; however, this approach may not be adequate when precipitation of metals occurs.
